USB
Type-C and Power Delivery
UM2191
12/55
DocID030479 Rev 2
Table 4: Power options
Mode of operation
Nominal
voltage
Maximum
current
Maximum
power
Note
USB 2.0
5 V
500 mA
2.5 W
Default current based on
specification
USB 3.1
900 mA
4.5 W
USB BC1.2
up to 1.5 A
7.5 W
Legacy charging
USB Type-
C™
current at 1.5 A
1.5 A
Support high power devices
USB Type-
C™
current at 3 A
3 A
15 W
USB PD
up to 20 V
up to 5 A
100 W
Directional control and power
level management
1.8
Cable attachment and detachment detection and orientation
As stated in the USB Power Delivery specification, it is mandatory to determine the
orientation of an attachment; i.e., when one of the two CC pins detects a valid Rp/Rd
connection.
To detect an attachment, the source monitors both CC pins.
The pins are floating when nothing is attached, but when the sink is attached via the cable,
one CC line of the source is directly pulled-down (through the sink Rd), signalling that a
connection has been made (see
Figure 6: "Pull up/down CC detection"
).
Hence, once connection is established, a voltage divider is set between source pull-up
resistor Rp and sink pull-down resistor Rd, fixing the voltage level on the CC line for the
communication signals.
Figure 6: Pull up/down CC detection
At the same time, the orientation of the plug, and consequently of the cable, is defined
according to which CC line (CC1 or CC2) detects a valid resistance after the attach event.
The figure above shows an unflipped cable orientation.
Moreover, the full-featured cable, exposing an Ra resistor, connects the V
CONN
pins to
ground.